A key principle in orthogonal frequency division multiple access (OFDMA) communication systems is that the total operating bandwidth is divided into non-overlapping sub-bands, also called resource blocks (RBIs), where transmissions for user equipment (UE) occur in an orthogonal (i.e., not mutually interfering) manner. Each RE can potentially carry data to a different UE. More typically, each UE having a sufficiently high signal-to-interference and noise ratio (SINR) will use a well-chosen set of RBs, so that the spectral efficiency of the transmission is maximized according to the operating principle of a scheduler.
By scheduling each UE on RBs where it has high SINR, the data rate transmitted to each UE, and therefore the overall system throughput, can be optimized according to the scheduling principle. To enable more optimum frequency domain scheduling of UEs in the RBs of the operating bandwidth, each UE feeds back a channel quality indicator (CQI) it might potentially experience for each RB or each combination of RBs to its serving base station (Node B). Additionally, a transmission rank indicator (RI) that determines the number of data layers multiplexed in the spatial domain is also fed back. Improvements in the selection and feed back of rank and channel quality indicators would prove beneficial in the art.